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- noun Christianity A member of fanatical bands of
predatory peasantsthat flourished in North Africa in the 4th century. They were associated with Donatistsand sought death by martyrdom.
Sorry, no etymologies found.
I never knew one contend earnestly for a toleration of dissenters, but was so himself; nor any for their suppression, but were themselves of the persuasion which prevaileth: for if otherwise, this latter would argue a Circumcellion  fury, willfully to seek their own ruin; the former so much charity, and commiseration of the condition of mortality as in these days would procure of the most no other livery but a fool's coat.
The Sermons of John Owen 1616-1683 1968
Theodoret says a Circumcellion was accustomed to announce his intention of becoming a martyr long before the time, in order to be well treated and fed like a beast for slaughter.
Primianus of Carthage; of Rogatists, a Mauretanian sect, of mild character, because no Circumcellion belonged to it; the Rogatists were severely punished whenever the Donatists could induce the magistrates to do so, and were also persecuted by Optatus of Timgad.
The lower and middle classes spoke Punic, and the Circumcellion heretics were to be among the last of its defenders.
The Catholic Encyclopedia, Volume 1: Aachen-Assize 1840-1916 1913